When President Obama took office, he faced an Iran that had mastered the nuclear fuel cycle, had constructed a covert uranium enrichment facility inside a mountain, was on its way to installing nearly 20,000 centrifuges for uranium enrichment, was developing advanced centrifuges and was building a heavy-water reactor that could produce weapons-grade plutonium. If Iran wanted to develop a nuclear weapon, it was already well down that road and the international community had little insight...